In recent years, data relay devices have been developed which efficiently relay pieces of communication information, as data, transmitted/received in communication protocols which are different from each other. An example of such data relay devices includes, for example, a communication message conversion device disclosed in Patent Literature 1 (hereinafter, referred to as conventional art).
The conventional art efficiently relays data transmitted/received through one communication line in accordance with a CAN (Controller Area Network) protocol, and data transmitted/received through the other communication line in accordance with the FlexRay (registered trademark) protocol, from the one communication line to the other communication line, and vice versa. In the conventional art, the hardware is configured such that data can be relayed efficiently, and the number of relays of data which is less important is reduced or the like. Further, in order to efficiently relay a frame received from the other communication line in accordance with FlexRay protocol to the one communication line in accordance with the CAN protocol, the conventional art transmits/receives such a frame received in accordance with the FlexRay protocol in a format which can be easily divided.    [PATENT LITERATURE 1] Japanese Patent Laid-open Publication No. 2007-174053